Impact attenuation safety cushion and system

ABSTRACT

Compositions and designs useful for fabricating safety cushion and mat assemblies which have effective protection against injuries to persons falling from a height up to seven feet are disclosed. The safety cushion compositions have a shore hardness of about 68, comprises an ethylene/propylene rubber, an activator, an accelerator, a plasticizer, a vulcanizer, a filler, a processing aid agent and optionally a colorant or a whitener. In addition, compositions useful for fabricating a reinforced rubber anchor for securing the safety cushion and mat assemblies to the ground are disclosed. The rubber anchor composition has a shore hardness of about 73 and comprises a natural rubber, a processing aid agent, a plasticizer, a filler, an antioxidant, an antiozonant, an activator, an accelerator, a vulcanizer, an inhibitor and optionally a colorant or a whitener. Methods of fabricating the safety cushion, mat assemblies and securing anchors described above improves the fabricating process so that larger pieces of safety cushion can be molded and that the composition material does not stick to the mold thereby increases production efficiency.

1. BACKGROUND OF THE INVENTION

1.1. Technical Field

The present invention relates to chemical compositions useful forfabricating safety cushions, mats formed from an assembly of such safetycushions and anchoring bolt for securing such mat to the ground. Moreparticularly, the safety cushion and mat assembly meet and exceed theASTM Standard Specification F1292-91 for impact attenuation of surfacesystems under and around equipment located in playgrounds, roof-toprecreational areas, running tracks (indoor and outdoor), health club,aerobic dance facilities, veterinary hospitals, gymnasium or the like.

As used herein, the term "safety cushion" means a shock attenuatingcoverings for floor and ground surface that can be used to reduce thethreat of danger to a person falling off equipment by reducing theimpact force to the head to less than 200 g's from a dropheight of up toseven feet.

As used herein, the term "mat" means an assembly of individual safetycushions which are interlocked together in such a manner to cover asurface of a rectangular, circular, oval, L's, T's, crosses or othergeometrical shapes.

As used herein, the term "around equipment" means the area under andsurrounding equipment established as protection from falls fromequipment.

As used herein, the term "acceleration" means the time rate change ofvelocity.

As used herein, the term "deceleration" means the time rate of reductionof velocity.

As used herein, the term "g" means acceleration into gravity at theearth's surface at sea level (32 ft/s (9.8 m/s)).

As used herein, the term "g-max" means the multiple of "g" thatrepresents a maximum deceleration experienced during an initial impact.

As used herein, the term "headform" means the striking part of a testingapparatus.

As used herein, the term "impact attenuation" means the ability of asurface system to reduce and dissipate the energy of an impacting body.

As used herein, the term "dropheight" is the vertical distance of theheadform above the safety cushion from which the headform is acceleratedunder gravity before impacting the safety cushion.

1.2 Description of Background Art

Shock-absorbing safety cushions and mat assemblies are greatly needed inmany applications where equipments are located, such as in school yardsand playgrounds. In these areas, severe injuries have been caused topersons by losing foothold from an equipment and by falling from playapparatus onto a hard ground surface, such as an asphalt or concretesurface. As a result, many efforts are being made to find an improvedsurface covering for playgrounds, recreational and industrial floors orthe like, which will give protection against such injuries.

Indeed, the Consumer Product Safety Commission has determined that therisk of serious injury due to a head-first fall is minimal when theamount of force the head absorbs is 200 g's or less.

A child landing on asphalt from a height of seven feet would impact witha force of several thousand g's. In fact, hitting asphalt from a heightof only two inches incurs a g-force of over 300.

Various types of surface coverings have been attempted to solve thisproblem. Such efforts include mats made of resilient material, rubbergranules or ground up tires, but none, prior to the present invention,was able to reduce the impact force of a headform to less than 200 g'sfrom a dropheight up to seven feet.

Thus, there is a continuous and urgent need for chemical composition anddesign for a safety cushion and mat assembly that can be used to reducethe impact g-force to the head to less than 200 g's from a dropheight upto seven feet.

Moreover, a need also exists for chemical composition and design foranchoring system to secure the safety cushion and mat assembly to theground, thereby reducing the danger of slippage and theft by having thesafety cushion or mat assembly pulled up.

2. SUMMARY OF THE INVENTION

The present invention provides chemical compositions and designs usefulfor fabricating safety cushion and mat assemblies which have effectiveprotection against injuries to persons falling from a height up to sevenfeet by reducing the impact g-force to less than 200 g's.

The present invention specifically provides chemical compositions anddesign useful for fabricating safety cushions and mat assembliesconforming to ASTM Standard Specification F 1292-91 by performing theTest Method F355, Procedure C (metal headform) from a dropheight up toseven feet.

The present invention further provides chemical compositions and designsuseful for fabricating the reinforced rubber anchor for securing thesafety cushion and mat assemblies to the ground.

In addition, the present invention provides a safety cushion systemcomprising a mat formed from an assembly of safety cushions andreinforced rubber anchors of the above compositions that resists wear,weather, cutting, puncture, pulling and fire.

Specifically, the present invention provides compositions useful forfabricating safety cushions and mat assemblies and has a shore hardnessof about 68±3 wherein the composition comprises an ethylene/propylenerubber, an activator, an accelerator, a plasticizer, a vulcanizer, afiller, and optionally a colorant or a whitener.

The present invention also provides compositions useful for fabricatingthe reinforced rubber anchor for securing the safety cushion and matassemblies to the ground and has a shore hardness of about 73 whereinthe composition comprises a natural rubber, a processing aid agent, aplasticizer, a filler, an antioxidant, an antiozonant, an activator, anaccelerator, a vulcanizer, an inhibitor and optionally a colorant or awhitener.

Moreover, the present invention provides a method of fabricating safetycushions and mat assemblies whereby during the fabricating process, thematerial does not stick to the mold, has good hot tear strength andoutstanding demolding capability.

3. BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention may be more fullyunderstood from the following detailed description, taken together withthe accompanying drawings, wherein similar characters refer to similarelements throughout and in which:

FIG. 1 is a pictorial view of playground equipment installed on safetycushions made according to the present invention.

FIG. 2 is an exploded perspective view of a safety cushion having a rampportion, the safety cushion being cutaway to show its innerconstruction.

FIG. 3 is a cross sectional elevational view of a safety cushion securedto a concrete slab.

FIG. 4 is a partially cutaway bottom view of the safety cushion.

4. DESCRIPTION OF THE PREFERRED EMBODIMENT

A safety cushion 10 embodying the features of the present invention isshown in FIGS. 1-4. Referring to FIG. 1, a number of individual safetycushions 10 are assembled to form a mat 12 to be placed underneathplayground equipment. The mat 12 surrounds the playground equipment suchthat a child 80 falling from a tire swing 82, a slide 84 or an elevatedstructure 86 will come into contact with the mat 12 which will preventserious injury by absorbing the shock from the fall.

Although the exemplary embodiment of the safety cushions disclosedherein are shaped primarily in a square, the cushions may be made in anyshape and accordingly the mat 12 may be shaped to fit any desired area.Border pieces 14 having wedge shaped ramps 16 may also be added to themat to provide a trip free transition from an area 18 surrounding themat 12.

Referring to FIG. 4, the underside of the safety cushion 10 is seen tocomprise a plurality of rectangular pockets 20 having a waffleconstruction. Preferably, the pockets 20 are square. The pockets 20 areformed by a series of parallel ribs 22 which are molded integrally withand perpendicular to the underside of the safety cushion 10 and a seriesof parallel cross-ribs 24 which are molded integrally with the undersideof the safety cushion 10 in the same manner as the ribs 22, butperpendicularly intersect the ribs 22. Safety cushion 10 is also boundedby end walls 26.

The safety cushion 10 has a surface layer 28 that is supported by theribs 22, cross-ribs 24 and end walls 26. Except for the ramps 16 of theborder pieces 14, the ribs 22, cross-ribs 24 and end walls 26 generallyhave the same vertical depth so that all share in supporting the surfacelayer 28 when the safety cushion 10 is resting on a relatively evensurface, such as a concrete slab 70. Also, since the ribs 22, cross-ribs24 and end walls 26 are of equal depth, the pockets 20 have co-planarlower edges 30. This gives the pockets a suction cup characteristicwhich enables them to establish a connection with the surface 70 coveredby the cushion, thereby assisting in holding the cushion to the surface.Preferably, the top of the surface layer 28 is formed with a pluralityof individual raised buttons 34 to prevent slippage. In the preferredembodiment, the raised buttons are formed in parallel rows and the ribs22 intersect the underside of the safety cushion 10 at a locationbetween a respective pair 23 of said parallel rows of raised buttons 34(see FIG. 2). Similarly, the cross-ribs 24 intersect the underside ofthe safety cushion 10 at a location between a respective pair 25 ofparallel rows.

The wedge shaped ramp 16 of the border piece 14 also has a waffleconstruction (see FIG. 2). In this case, corresponding ribs 22' of theramp 16 are reduced in depth to support a ramp surface layer 36 of theramp on the surface 70. Corresponding cross-ribs 24' of the ramp aretapered to also support the ramp surface layer 36.

Referring to FIG. 3, the lower edge 30 of each rib 22 contacts thesurface 70. Each rib also has an upper surface 40 molded to the surfacelayer 28 of the underside of safety cushion 10 and two walls 42, 44.Preferably, the walls 42, 44 are tapered at about a 3° angle, with thewalls 42, 44 converging as they approach the lower edge 30. Eachcross-rib 24 of the safety cushion may be similarly molded.

In the preferred embodiment, each safety cushion 10 is a 48 inch by 48inch square having a total depth of 13/4 inches. The surface layer 28 is1/4 inch thick including 1/16 inch raised buttons 34. Each raised button34 has a 3/8 inch diameter and there are four raised buttons per squareinch on surface layer 28. The ribs 22 and cross-ribs 24 are spaced at 1inch intervals and are 11/2 inches in height. The lower edge 30 of theribs 22 and cross-ribs 24 is 1/10 of an inch wide and the walls of theribs and cross-ribs diverge at a 3° angle from vertical from the loweredge 30. The end walls 26 are 1/20 inch thick.

Anchoring bolts 50, shown in FIGS. 2 and 3, are used to secure thesafety cushions to a supporting surface. Each anchoring bolt 50 includesa head 52 integrally molded to a bolt portion 54. The anchoring bolt 50is preferably made from a different rubber compound as the safetycushion 10. The bolt 50 may be injection molded around a nylon cord 56or other material located along the axis of the bolt portion 54 toimprove the tensile properties of the anchoring bolt 50. The head 52 maybe formed with raised buttons 60, similar to the raised buttons 34 onthe surface layer 28 of the safety cushion 10.

The safety cushion 10 may be molded with a recessed portion 62 for eachanchoring bolt 50. The recessed portion 62 includes a wall 64 and a seat66 defining an opening 68 for receiving the bolt portion 54 of theanchoring bolt, but not the head 52 of the anchoring bolt. The thicknessof the wall 64 and the seat 66 is preferably about 1/4 inch. The depthof the recessed portion 62 should be slightly greater than the thicknessof the head 52 of the anchoring bolt 50 to prevent tripping over theanchoring bolt when it is installed in the safety cushion.

In the case of the 48 inch by 48 inch safety cushion referred toearlier, four anchoring bolts are sufficient to secure the cushion to asupporting surface. Preferably, a bolt is placed in each corner 5 inchesfrom each edge. For smaller safety cushions, e.g., 24 inches by 24inches, two anchoring bolts may be used along a center line of thecushion, each bolt being 4 inches inward from an edge of the cushion.Preferably, each anchoring bolt is about 4 11/16 inches long, the headof each anchoring bolt is about 13/4 inches in diameter and each boltportion is at least 9/16 inches in diameter.

Referring to FIG. 3, the safety cushion is shown installed on theconcrete slab 70. The anchoring bolt 50 is inserted through the recessedportion 62 of the safety cushion 10 and may be glued to the seat 66. Ahole 72 is drilled into the concrete slab 70. Preferably, the hole inthe slab is approximately twice the diameter of the bolt portion 54 ofthe anchoring bolt 50. The anchoring bolt is then grouted into the holein the concrete slab. Preferably, the bolt portion 54 has indentations64 to prevent the anchoring bolt from pulling out of the grout andconcrete slab.

In the present invention, it has been found that a specific combinationof compositions is required to fabricate the safety cushion and matassembly so as to reduce the impact force of a headform to less than 200g's from a dropheight of up to seven feet.

The ethylene/propylene rubber used in the safety cushion composition maybe of any type, but is preferably of the non-reactive type andpreferably, a sequence teropolymer polymerized from ethylene, propylenewith about 1-6% diene (EPDM). Exemplary ethylene-propylene rubbercompounds include BUNA EPDM, such as AP 147 sold by Huls America. Theethylene/propylene rubber may be used alone in the composition or as amixture with other compounds, such as a different olefin or polyolefin.

A variety of activators appropriate to promote the curing of the presentsafety cushion compositions may be used. Such activators include zincoxide, stearic acid, and preferably, a combination thereof.

A variety of accelerator appropriate to accelerate the curing of thepresent safety cushion compositions may be used. Such acceleratorsinclude N-oxydiethylene benzothiazole-2-sulfenamide, sold as Amaxcommercially; tetraethylthiuram disulfide, known as methyl TUADS, andpreferably, a combination thereof.

A plasticizer, preferably of the liquid plasticization materialappropriate to plasticize the present safety cushion compositions may beused. Exemplary are naphthenic hydrocarbon oil, known commercially ascyclolube 413 oil, paraffinic oil known commercially as Sunpar 2280 oil,naphthenic oils known commercially as Shellflex 371 or the like.

The present safety cushion compositions also include a vulcanizationagent, preferably sulfur.

For many applications, the safety cushion compositions are preferablyfilled, and preferably contains loading of about 100-300 parts of fillerper 100 parts of ethylene/propylene rubber. The filler may comprise oneor more of the several conventional fillers, preferably is the use of agrinded form of rubber from tires known commonly as #1 Buffing. Otherfillers preferably employed in lesser amounts in combination with #1buffing as the filler include carbon blacks, known commercially as N650Black, and N300 Black. If the color for the cushion is desired to beother than black, then optionally, a colorant, such as red or yellowiron oxide, or a whitener, such as titanium dioxide may be used.

Optionally, a processing aid agent appropriate to assist processing ofthe present safety cushion compositions may be used. Such processing aidagents include common blend of rubber compatible non-hardening syntheticresins and fatty acid soaps, known commercially as Struktol EP 52, fromStruktol Co.

Safety cushion compositions of the present invention may be prepared byany conventional method. For example, the safety cushion may becompression molded. In general, the uncured rubber of the composition isbeing placed in the mold cavity before the mold is closed. The mold isthen assembled as far as possible and placed in a hydraulic press. Thepress completes the closing of the mold, causes the rubber to flow andcompletely fill the cavity. After the mold has been under pressure forthe prescribed amount of time at the designated temperature, the mold isremoved from the pressure and disassembled to remove the rubber parts.Molding conditions for the safety cushion of the present invention mayrange from about 300-2000 psi pressure, preferably about 1200 psi percavity area, 270° to 360° F. temperature, preferably 300° F., cure timefrom five minutes to one hour, preferably about 15 minutes. Any suitablecompression molding machine equipped with the appropriate mold may beemployed.

The ratio between the various ingredients need to be controlled. In thefollowing disclosure, unless otherwise stated, all parts by weight ofthe ingredients are in reference to the total weight of theethylene/propylene rubber(i.e. the total weight of theethylene/propylene rubber is taken to be 100 parts by weight) used inthe composition. However, about 70-130 parts by weight of theethylene/propylene rubber can be used in the safety cushion composition.

Whatever activators are employed, generally are applied at levelssufficient to provide sufficient activity and processing stability toimprove long term high heat exposure of the safety cushion compositionunder anticipated molding conditions. Generally amount between 1-10parts by weight is sufficient, preferably about 5-8 parts by weight.

The amount of accelerator used are sufficient to provide a reasonablerate of curing of the present safety cushion composition. Generallyamount between 1-10 parts by weight is sufficient, preferably about 2-6parts by weight.

A plasticizer is used to enhance the processing characteristics of theresulting safety cushion composition. The plasticizer is used in anamount sufficient to give the desired plasticizing efficiency andperformance under anticipated molding conditions. Usually amount between30-70 parts by weight is sufficient, preferably about 40-50 parts byweight.

Whatever vulcanization agent is used, is generally applied at levelssufficient to vulcanize the safety cushion composition under anticipatedmolding conditions. Usually amount between about 0.1-3 parts by weightis sufficient, preferably about 0.8-1.2 parts by weight.

The total amount of filler used may vary from 100-300 parts by weight,and preferably about 170-230 parts by weight. Also, preferably, betweenabout 90-110 parts by weight is a grinded form of rubber from tires suchas #1 Buffing. If the color of the cushion is desired to be other thanblack, then the appropriate colorant will be used in place of the carbonblack in an amount sufficient to give the cushion the desired color.

Optionally, a processing aid agent may be used to assist processing ofthe present safety cushion composition. The processing aid agent ifused, will be generally in an amount of between 1-10 parts by weight,preferably 2-6 parts by weight.

The present invention also relates to compositions useful forfabricating the anchoring bolt used to secure the safety cushions andmat assembly to the ground to prevent cushion dislocation or theft.

The natural rubber used in the composition of the anchoring bolt may beof any type, but is preferably of the non-reactive type. Exemplarynatural rubber include SIR 20, an Indonesian rubber with dirt content ofless than 0.2% by weight, #1 smoked sheets which is a processed bulk ofnatural rubber lattice or preferably a combination thereof. To improvethe processing properties of the natural rubber, a styrene-butadieneresin-known commercially as Pliolite S6B is added. The natural rubbermay be used alone in the composition or as a mixture with othercompounds, such as a synthetic rubber.

A variety of processing aid agents appropriate to assist processing ofthe present anchoring bolt composition may be used. Such processing aidagents include pentachlorothiophenol, a peptizer, commercially sold asRenacit #7, alkyl phenol formaldehyde resin, commercially known as Sp1068 resin, or a combination thereof.

A plasticizer, preferably of the liquid plasticization materialappropriate to plasticize the present anchoring bolt compositions may beused. Exemplary is extracts from pine, known commonly as pine tarmedium.

For many applications, the anchoring bolt compositions are preferablyfilled, and preferably contains loading of about 10 to 150 parts offiller. The filler may comprise one or more of the several conventionalfillers preferably is the use of carbon black and amorphous silica.Exemplary are carbon blacks known commercially as N339 Black andamorphous silica known commercially as Hisil 243, respectively. If thecolor desired for the anchoring bolt is other than black, thenoptionally a colorant, such as red or yellow iron oxide, or a whitener,such as titanium dioxide can be used in place of the carbon black in thecomposition.

To improve the resistance to sunlight and weather of the safety cushion,an antioxidant together with an antiozonant are added to the anchoringbolt compositions. Antioxidant, such as polymerized1,2-dihydro-2,2,4-trimethylquinoline, orN-phenyl-N(1,3,dimethylbutyl)p-phenylene diamine, known commercially asAgerite Resin D and Flexzone 7F respectively, and antiozonant, knowncommercially as Sunproof Extra™ (a mixture of waxy materials fromUniroyal Chemical Co.) are generally preferred.

A variety of activators appropriate to promote the curing of the presentanchoring bolt compositions may be used. Such activators include zincoxide, stearic acid, and preferably, a combination thereof.

A variety of accelerator appropriate to accelerate the curing of thepresent anchoring bolt compositions may be used. Such acceleratorsinclude 4-morpholinyl-2-benzothiazole disulfide, known commercially asMorfax, 4',4'-dithiodimorpholine, known commercially as Sulfusan R andmethyl TUADS.

The present anchoring bolt compositions also include a vulcanizationagent, preferably sulfur treated with magnesium carbonate, knowncommercially as Spider sulfur.

To control the rate of vulcanization and to improve processing of theanchoring bolt composition, a prevulcanized inhibitor, such asN-cyclohexylthiophthalamide, known commercially as P.V.I. is alsoincluded in the composition.

Anchoring bolt compositions of the present invention may be prepared byany conventional method. The natural rubber, processing aid agent,plasticizer, filler, antioxidant, antiozonant and the stearic acidactivator were first mixed together and stir for 24 hours to make amaster batch. After the master batch was made, the rest activators,accelerator, vulcanizer and inhibitor were then added to the mixture.The anchoring bolt composition may be compression molded similar to thesafety cushion compositions as described earlier in this application.Molding conditions for the anchoring bolt compositions may range fromabout 300-2000 psi pressure, preferably about 1200 psi per cavity area,270° to 360° F. temperature, preferably 300° F., cure time from fiveminutes to one hour, preferably about 15 minutes. Any suitablecompression molding machine equipped with the appropriate mold may beemployed.

The ratio between the various ingredients need to be controlled. In thefollowing disclosure, unless otherwise stated, all parts by weight ofthe ingredients are in reference to the total weight of the naturalrubber (i.e. the total weight of the natural rubber is taken to be 100parts by weight) used in the composition.

The total amount of natural rubber used is generally taken to be 100parts but 90-110 parts by weight of the natural rubber may be used, inthe composition. The natural rubber may vary from 0-100 parts by weightof SIR 20 or #1 smoked sheets, and preferably a mixture of a ratiobetween 0.8-1.2.

The amount of processing aid agents used to improve the processing ofthe anchoring bolt compositions generally is about 2-20 parts by weight,preferably 8-12 parts by weight.

A plasticizer is used in an amount sufficient to give the desiredplasticizing efficiency and performance under anticipated moldingconditions. Usually amount between 0.5-10 parts by weight is sufficient,preferably about 1-3 parts by weight.

The total amount of filler used may vary from 10-100 parts by weight,preferably about 60-80 parts by weight. If the color of the anchoringbolt is desired to be other than black, then the appropriate colorantwill be used in place of the carbon black in an amount sufficient togive the cushion the desired color.

Whatever antioxidant and antiozonant is used, is generally applied atlevels sufficient to provide the necessary resistance to sunlight andweather of the anchoring bolt. Usually amount of antioxidant orantioxonant between 1-10 parts by weight is sufficient, preferably about1-5 parts by weight.

The amount of activator employed are at levels sufficient to providesufficient activity and processing stability to improve long term highheat exposure of the anchoring bolt composition under anticipatedmolding conditions. Generally, amount between 3-10 parts by weight issufficient, preferably 6-8 parts by weight.

The amount of accelerator used are sufficient to provide a reasonablerate of curing of the present anchoring bolt composition. Generally,amount between 1-6 parts by weight is sufficient, preferably about 2-4parts by weight.

Whatever vulcanization agent is used, is generally applied at levelssufficient to vulcanize the safety cushion composition under anticipatedmolding conditions. Usually amount between about 0.1-3 parts by weightis sufficient, preferably about 0.4-0.8 parts by weight.

The amount of pre-vulcanized inhibitor used are sufficient to maintainthe appropriate rate of vulcanization prior to compression molding.Generally, amount between about 0.01 to 3 parts by weight is sufficient,preferably about 0.05-0.15 parts by weight.

The present invention is not restricted to the above ingredients but mayinclude other ingredients which do not detract from impact forcereduction properties of the safety cushion and the anchoring bolt.Accordingly, other natural rubber polymers, organic or inorganicmaterials or the like may be added under the above conditions.

The following non-limiting examples further illustrate the presentinvention. All parts are by weight in reference to the total weight ofthe natural rubber used in the composition unless otherwise indicated.

The "impact attenuation test" referred to in the following examples isthe same as that of ASTM F 355 Test Method for Shock AbsorbingProperties of Playing Surface Systems and Materials and the procedureused as specified in paragraph 4 of ASTM Standard Specification F1292-91, which is hereby incorporated by reference. The test generallyinvolves measuring the impact force of a metal headform according totest method F 355, Procedure C at various dropheights and testtemperatures. First, the test apparatus is calibrated to zero.Laboratory samples (safety cushion) fabricated using a specificcomposition was preconditioned at 50±10% relative humidity 72±5° F.(23±3° C.) for a minimum of 24 hours prior to beginning testing. Forsamples to be tested at different temperatures, the samples wereconditioned at such temperature for 4 hr minimum. Testing were startedwithin 1 minute of taking samples out of the environmental chamber witha time interval between drops of 3±0.25 minutes shall be conditioned.After the test apparatus was calibrated to zero, the metal headform wasthen raised to the desired dropheight. The preconditioned safety cushionsample to be tested is then placed on the floor directly underneath themetal headform. The metal headform was then released from the dropheightand allowed to impact the sample under gravity. The deceleration forcein g's was then recorded by the recording system of the apparatus. Theimpact test was repeated for different heights in whole foot increments,i.e. 1,2,3 . . . n, that give a deceleration force of 200-g max or less.The impact test consists of three drops at the same impact site, at eachheight, and the average of the deceleration force recorded for thesecond and third drops are used to determine the impact attenuation. Ifthe average of the second and third deceleration force recorded is lessthan or equal to 200 g's, then the safety cushion is considered safewithin the meaning of the term as used herein.

4.1. EXAMPLE 1

Safety cushion was prepared from the composition indicated in table 1.Composition 1 is a starting formulation and has a shore hardness of only50±5. When the impact attenuation test was performed on the safetycushion fabricated using composition 1, the impact force is 220 g forthe first drop test.

                  TABLE 1                                                         ______________________________________                                        SAFETY CUSHION COMPOSITION 1                                                  SHORE HARDNESS = 50 ± 5                                                             INGREDIENTS                                                                              PARTS BY WEIGHT                                           ______________________________________                                        Polymer    Royalene 509.sup.a                                                                         64.89                                                            Royalene 505.sup.b                                                                         19.15                                                            SBR 1712.sup.c                                                                             19.20                                                 Activator  Zinc Oxide   4.00                                                             Stearic acid 1.00                                                  Accelerator                                                                              Amax.sup.d   1.50                                                             Butyl Zimate.sup.e                                                                         1.00                                                             D.P.G..sup.f 0.60                                                             Cumate.sup.g 0.40                                                  Plasticizer                                                                              Cyclolube 85 oil.sup.h                                                                     105.88                                                Vulcanizer Sulfur       3.50                                                  Processing aid                                                                           Struktol WB 212.sup.i                                                                      1.00                                                  Filler     Ionic clay   58.82                                                            #1 Buffings.sup.j                                                                          117.64                                                           N660 Black.sup.k                                                                           59.29                                                            Austin Black.sup.l                                                                         29.41                                                 ______________________________________                                         .sup.a Royalene 509, 70/30 EP ratio, ENB third monomer, Uniroyal Chemical     .sup.b Royalene 505, 57/43 EP ratio, ENB third monomer, Uniroyal Chemical     .sup.c SBR 1712, Styrene Butadiene                                            .sup.d Noxydiethylene benzothiazole2-sulfenamide                              .sup.e Zinc dibutyldithiocarbamate, R. T. Vanderbilt                          .sup.f Symmetrical diphenylguanidine, American Cyanamid                       .sup.g Copper dimethyldithiocarbamate, R. T. Vanderbilt                       .sup.h Napthenic hydrocarbon oil                                              .sup.i Blend of rubber compatible nonhardening synthetic resins and fatty     acid soaps                                                                    .sup.j Grinded form of rubber from tires                                      .sup.k Carbon, J. M. Huber                                                    .sup.l Ground coal, Harwick                                              

4.2. EXAMPLE 2

Safety cushion was prepared from the composition indicated in Table 2.The Buffing was removed from composition 2 and the filler Austin Blackwas replaced with clay. Safety cushion fabricated from composition 2 hasa shore hardness of 60±5. When the impact attenuation test was performedon the safety cushion fabricated using composition 2, the impact forceis 168, 215 and 225 g's for the first, second and third drop testrespectively.

                  TABLE 2                                                         ______________________________________                                        SAFETY CUSHION COMPOSITION 2                                                  SHORE HARDNESS = 60 ± 5                                                             INGREDIENTS                                                                              PARTS BY WEIGHT                                           ______________________________________                                        Polymer    EPCAR ® 5875.sup.m                                                                     80.0                                                             Royalene 400.sup.n                                                                         80.0                                                  Activator  Zinc oxide   20.0                                                             Stearic acid 0.5                                                   Accelerator                                                                              Amax         1.5                                                              Methyl TUADS 1.0                                                              Butyl Zimate 0.4                                                              Carbowax 3350                                                                              4.0                                                   Processing aid                                                                           #371 oil     20.0                                                  Vulcanizer Sulfur       1.0                                                   Filler     Ionic clay   75.0                                                             Nucap 100°                                                                          75.0                                                             N550 Black   10.0                                                  ______________________________________                                         .sup.m EPCAR ® 5875 EPDM from Goodrich                                    .sup.n Royalene 400 68/32 Ethylene/propylene ratio                            .sup.o Nucap 100 Mercapto silane, functional hydrated aluminum silicate,      J. M. Huber                                                              

4.3. EXAMPLE 3

Safety cushion was prepared from the composition indicated in Table 3.Safety cushion fabricated from composition 3 has a shore hardness of75±2. When the impact attenuation test was performed on the safetycushion fabricated using composition 3, the impact force is 198, 231 and236 g's for the first, second and third drop test respectively.

                  TABLE 3                                                         ______________________________________                                        SAFETY CUSHION COMPOSITION 3                                                  SHORE HARDNESS = 75 ± 2                                                             INGREDIENTS                                                                              PARTS BY WEIGHT                                           ______________________________________                                        Polymer    Royalene 400 50.0                                                             EPCAR ® 5875                                                                           50.0                                                             Royalene 622.sup.p                                                                         70.0                                                  Activator  Zinc oxide   5.0                                                              Stearic acid 1.0                                                   Accelerator                                                                              Methyl zimate                                                                              1.5                                                              MBTS.sup.q   1.0                                                              Monex.sup.r  1.5                                                   Plasticizer                                                                              Cyclolube 85 oil.sup.s                                                                     80.0                                                  Filler     Omyacarb 10.sup.t                                                                          100.0                                                            N650 Black   80.0                                                             N774 Black   200.0                                                 Vulcanizer Sulfur       2.0                                                   ______________________________________                                         .sup.p Royalene 622 75/25 Ethylene/propylene ratio                            .sup.q MBTS: mercaptobenzothioazol disulfide                                  .sup.r Monex: tetramethylthiuram monosulfide, Uniroyal chemical               .sup.s Cyclolube 85 oil: naphthenic hydrocarbon oil, Witco Golden Bear        div.                                                                          .sup.t Omyacarb 10: calcium carbonate                                    

4.4. EXAMPLE 4

Preferred safety cushion compositions with a shore hardness of 68±3 wereprepared from compositions indicated in Table 4.

                  TABLE 4                                                         ______________________________________                                        SAFETY CUSHION COMPOSITION 4, 5 and 6                                         SHORE HARDNESS = 68 ± 3                                                              No. 4     No. 5      No. 6                                          ______________________________________                                        POLYMER                                                                       Royalene 400 50                                                                           Buna AP147  Buna AP147.sup.u                                                  100         100                                                   Royalene 512 75                                                               ACTIVATOR                                                                     Zinc Oxide  5.0         5.0        5.0                                        Stearic acid                                                                              1.5         1.5        1.5                                        PLASTICIZER                                                                   HPO 603 oil 20 HPO 603 oil                                                                            45         Cyclolube                                                                     413 oil.sup.v 45                           VULCANIZER                                                                    Sulfur      1.0         1.0        1.0                                        ACCELERATOR                                                                   Amax        3.0         3.0        3.0                                        Methyl TUADS                                                                              0.5         0.5        0.5                                        FILLER                                                                        #1 Buffings 100         100        100                                        N650 Black  45          45         45                                         N300        50          50         50                                         PROCESSING                                                                    AID AGENT                                                                     Struktol EP52.sup.w                                                                       5                                                                             (Wingtack 95) 1                                                   ______________________________________                                         .sup.u Buna AP147: Ethylene/propylene rubber, Huls America                    .sup.v Cyclolube 413 oil: Naphthenic hydrocarbon oil, from Witco Golden       Bear                                                                          .sup.w Struktol EP52: blend of rubber compatible nonhardening synthetic       resins and fatty acid soaps, from Struktol                               

Composition 4 comprises the polymers of Royalene 400 & Royalene 512.Composition 6, on the other hand comprises the polymer BUNA AP 147. Bothcompositions 4 and 5 comprise the plasticizer of H.P.O. 603 oil.Composition 6 comprises the BUNA AP 147 polymer in combination with theplasticizer Cyclolube 413 oil. Table 4A summarizes the impactattenuation test conducted on safety cushion fabricated usingcompositions 4-6. As can be seen in Table 4A, safety cushion fabricatedfrom composition 4 failed the impact attenuation test at hightemperature (120° F.), while the safety cushion fabricated fromcomposition 5 failed the impact attenuation test at low temperature (30°F.). Only safety cushion fabricated from composition 6 passed the impactattenuation test at low, room and high temperatures.

                  TABLE 4A                                                        ______________________________________                                        IMPACT ATTENUATION TEST CONDUCTED                                             ON SAFETY CUSHIONS                                                            USING COMPOSITIONS 4, 5 and 6                                                                    COMPOSITIONS                                                                  No. 4                                                                              No. 5    No. 6                                        ______________________________________                                        A.  ROOM TEMPERATURE                                                              Drop Test            Impact Attenuation (g)                               No. 1                172    167      164                                      No. 2                194    178      185                                      No. 3                204    198      194                                      Average of (2 + 3) 199      188        189.5                                  B.  LOW TEMPERATURE (30° F.)                                               Drop Test            Impact Attenuation (g)                               No. 4                180    197      185                                      No. 5                192    205      191                                      No. 6                198    200      196                                      Average of (2 + 3) 195        202.5    193.5                                  C.  HIGH TEMPERATURE (120° F.)                                             Drop Test            Impact Attenuation (g)                               No. 7                164    159      148                                      No. 8                208    188      176                                      No. 9                220    199      194                                      Average of (2 + 3) 214        193.5  185                                      ______________________________________                                    

4.5. EXAMPLE 7

Anchoring bolt was prepared from the composition indicated in Table 5.Anchoring bolt fabricated from composition 7 has a shore hardness of76±3.

                  TABLE 5                                                         ______________________________________                                        COMPOSITION OF THE ANCHORING BOLT                                             SHORE HARDNESS = 76 ± 3                                                            INGREDIENTS PARTS BY WEIGHT                                           ______________________________________                                        Polymer   SIR 20.sup.1,A                                                                              50.0                                                            #1 Smoked sheets.sup.2,A                                                                    50.0                                                  Processing                                                                              Pliolite S6B.sup.3,A                                                                        6                                                     aid agents                                                                              Renacit #7.sup.4,A                                                                          0.4                                                             SP1068 resin.sup.5,A                                                                        3                                                     Plasticizer                                                                             Pine tar medium.sup.6,A                                                                     2                                                     Filler    N339 Black.sup.7,A                                                                          60                                                              Hisil 243.sup.8,A                                                                           10                                                    Antioxidant                                                                             Agerite resin D.sup.9,A                                                                     1.5                                                             Flexzone 7F.sup.10,A                                                                        1.5                                                   Antiozonant                                                                             Sunproof extra.sup.11,A                                                                     3                                                     Activator Stearic acid.sup.A                                                                          2.5                                                             Zinc oxide.sup.B                                                                            5                                                     Accelerator                                                                             Morfax.sup.12,B                                                                             1.5                                                             Sulfasan R.sup.13,B                                                                         0.8                                                             Methyl TUADS.sup.B                                                                          .4                                                    Vulcanizer                                                                              Spider Sulfur.sup.14,B                                                                      0.6                                                   Inhibitor P.V.I..sup.15,B                                                                             0.1                                                   ______________________________________                                         .sup.1 SIR 20: Standar Indonesian rubber with dirt content of ≦0.2     by weight                                                                     .sup.2 #1 Smoked sheets: processed bulk of natural rubber lattice;            .sup.3 Pliolite S6B: Styrene butadiene resin;                                 .sup.4 Renacit #7 Pentachlorothiophenol, a peptizer;                          .sup.5 SP1068 resin: Alkyl phenol formaldehyde resin, a tackifier resin;      .sup.6 Pine tar medium: extracts from pine;                                   .sup.7 N339 black: reinforced carbon black used in tire tread and hose        belts;                                                                        .sup.8 Hisil 243: precipitated hydrated amorphous silica;                     .sup.9 Agerite resin D: polymerized 1,2dihydro-2,2,4 trimethylquinoline;      .sup.10 Flexzone 7F: Nphenyl-N (1,3,dimethyl butyl) Pphenylene diamine;       .sup.11 Sunproof extra: mixture of waxy material from Uniroyal Chemical;      .sup.12 Morfax: 4morpholinyl-2-benzothiazole disulfide;                       .sup.13 Sulfusan R: 4',4dithiodimorpholine;                                   .sup.14 Spider sulfur: sulfur treated with magnesium carbonate;               .sup.15 P.V.I.: Ncyclohexylthiophthalamide, prevulcanized inhibitor;          .sup.A Ingredients were mixed toghether to form a master batch.               .sup.B After master batch A has been aged for 24 hours, ingredients were      then added for processing.                                               

The foregoing examples are intended to illustrate, without limitation,the chemical composition of the present invention, their preparation anduse for fabricating safety cushions, mat assemblies and anchoring boltsto prevent injuries to a person falling off playground equipment byreducing the impact g-force to the head of less than 200 g's from adropheight up to seven feet. It is understood that changes andvariations can be made therein without departing from the scope of theinvention as defined in the following claims.

What is claimed is:
 1. A method for forming anchoring bolt to secure asafety cushion that can be used to reduce the impact g-force to aheadform to less than 200 g's from a dropheight of up to seven feetcomprises the steps of:1. molding a composition comprising:(a) 90-110parts by weight of a natural rubber; (b) an effective amount ofprocessing aid agent sufficient to assist processing of said compositionunder molding conditions in an amount of 2-20 parts by weight; (c) aneffective amount of a plasticizer to give the desired plasticizingefficiency and performance under molding condition in an amount of0.5-10 parts by weight; (d) about 10-100 parts by weight of a filler;(e) an effective amount of an antioxidant to provide sufficientresistance to air oxidation in an amount of 1-10 parts by weight; (f) aneffective amount of an antiozonant to provide sufficient resistance tosunlight and weather in an amount of 1-10 parts by weight; (g) aneffective amount of an activator to provide processing and long termstability in an amount of 3-10 parts by weight; (h) between 1-6 parts byweight of an accelerator; (i) between 0.1-3 parts by weight of avulcanizer; and (j) between 0.01-3 parts by weight of a pre-vulcanizedinhibitor;
 2. 2. heating said composition to a temperature of 270° to360° F.3. compressing said composition at a pressure of 300-2000 psi percavity area; and
 4. curing said composition for 5-60 minutes.
 2. Amethod for forming anchoring bolt according to claim 1, wherein saidheating is effected at about 300° F.
 3. A method for forming anchoringbolt according to claim 2, wherein said compressing is effected at about1200 psi per cavity area.
 4. A method for forming anchoring boltaccording to claim 3, wherein said curing is effected for about 15minutes.
 5. A safety cushion system useful to reduce the impact g-forceto a headform from a dropheight up to seven feet comprises:(1) safetycushion having a shore hardness of 65-71 fabricated from a compositioncomprising:(a) 90-110 parts by weight of a ethylene/propylene rubber;(b) 5-8 parts by weight of a zinc oxide/stearic acid activator mixture;(c) 2-6 parts by weight of a N-oxydiethylenebenzothiazole-2-sulferamide/tetramethylthiuram disulfide acceleratormixture; (d) 40-50 parts by weight of a naphthenic hydrocarbon oilplasticizer; (e) 0.8-1.2 parts by weight of a sulfur vulcanizer; (f)170-230 parts by weight of a filler mixture of a grinded form of rubbertires and carbon black; and (2) an anchoring bolt to secure said safetycushion to the ground comprises:(a) 90-110 parts by weight of a mixtureof Indonesian rubber and a processed bulk of natural rubber lattice; (b)8-12 parts by weight of a styrene-butadieneresin/pentachlorothiophenol/alkylphenol formaldehyde processing aidagent mixture; (c) 1-3 parts by weight of a pine tar medium plasticizer;(d) 60-80 parts by weight of a carbon black and amorphous silica fillermixture; (e) 1-5 parts by weight of polymerized 1,2-diydro-2, 2,4-trimethylquinoline/N-phenyl-N (1, 3-dimethylbutyl) P-phenylene diamineantioxidant mixture; (f) 1-5 parts by weight of antiozonant; (g) 6-8parts by weight of a zinc oxide/stearic acid activate mixture; (h) 2-4parts by weight of a 4-morpholinyl-2-benzothiazole disulfide/4',4'-dithiodimorpholine/tetramethylthiuram disulfide accelerator mixture;(i) 0.4-0.8 parts by weight of a sulfur treated with magnesium carbonatevulcanizer; and (j) 0.05-0.15 parts by weight of aN-cyclohexylthiophthalamide pre-vulcanizer inhibitor.
 6. A safetycushion system useful to reduce the impact g-force to a headform from adropheight up to seven feet comprises:(1) safety cushion having a shorehardness of 65-71 fabricated from a composition comprising:(a) 70-130parts by weight of an ethylene/propylene rubber; (b) 1-10 parts byweight of a zinc oxide/stearic acid activator mixture; (c) 1-10 parts byweight of a N-oxydiethylenebenzothiazole-2-sulfenamide/tetramethylthiuram disulfide acceleratormixture; (d) 30-70 parts by weight of a naphthenic hydrocarbon oilplasticizer; (e) 0.1-3 parts by weight of a sulfur vulcanizer; (f)100-300 parts by weight of a filler mixture of a grinded form of rubbertires and a colorant; and (2) an anchoring bolt to secure said safetycushion to the ground comprises:(a) 90-110 parts by weight of a mixtureof Indonesian rubber and a processed bulk of natural rubber lattice; (b)2-20 parts by weight of a styrene-butadieneresin/pentachlorothiophenol/akylphenol formaldehyde processing aid agentmixture; (c) 0.5-10 parts by weight of a pine tar medium plasticizer;(d) 10-100 parts by weight of a colorant and amorphous silica fillermixture; (e) 1-10 parts by weight of a polymerized 1,2-diydro-2, 2,4-trimethylquinoline/N-phenyl-N (1,3-dimethylbutyl) p-phenylene diamineantioxidant mixture; (f) 1-10 parts by weight of a mixture of waxyantiozonant materials; (g) 3-10 pats by weight of a zinc oxide/stearicacid activate mixture; (h) 1-6 parts by weight of a4-morpholinyl-2-benzothiazole disulfide/4',4'-dithiodimorpholine/tetramethylthiuram disulfide accelerator mixture;(i) 0.1-3 parts by weight of a sulfur treated with magnesium carbonatevulcanizer; and (j) 0.01-3 parts by weight of aN-cyclohexylthiophthalamide pre-vulcanizer inhibitor.
 7. The safetycushion system of claim 6, wherein said ethylene/propylene rubber ofsaid safety cushion composition is further applied in an amount of90-110 parts by weight.
 8. The safety cushion system of claim 7, whereinsaid activator of said safety cushion composition is further applied ina total amount of 5-8 parts by weight.
 9. The safety cushion system ofclaim 8, wherein said mixture of zinc oxide and stearic acid of saidsafety cushion composition is of a ratio of 1-5:1.
 10. The safetycushion system of claim 9, wherein said accelerator of said safetycushion composition is further applied in a total amount of 2-6 parts byweight.
 11. The safety cushion system of claim 10, wherein said mixtureof N-oxydiethylene benzothiozole-2-sulfenamide and tetramethylthiuramdisulfide of said safety cushion composition is of a ratio of 4-8:1. 12.The safety cushion system of claim 11, wherein said plasticizer of saidsafety cushion composition is further applied in an amount of 40-50parts by weight.
 13. The safety cushion system of claim 12, wherein saidvulcanizer of said safety cushion composition is further applied in anamount of 0.8-1.2 parts by weight.
 14. The safety cushion system ofclaim 13, wherein said filler of said safety cushion composition isfurther applied in a total amount of 170-230 parts by weight.
 15. Thesafety cushion system of claim 14, wherein said filler of said safetycushion composition further comprises a mixture of a grinded form ofrubber from tires and carbon blacks.
 16. The safety cushion system ofclaim 15, wherein said mixture of said grinded form of rubber from tiresand carbon black of said safety cushion composition is of a ratio of0.5-2:1.
 17. The safety cushion system of claim 14, wherein saidcolorant of said safety cushion composition is selected from the groupconsisting of red iron oxide, yellow iron oxide, titanium dioxide andcarbon black.
 18. The safety cushion system of claim 14 wherein saidsafety cushion composition further comprises an effective amount of aprocessing aid agent sufficient to assist processing of said compositionunder molding conditions in an amount of 1-10 parts by weight.
 19. Thesafety cushion system of claim 18 wherein said processing aid agent ofsaid safety cushion is a blend of rubber compatible non-hardeningsynthetic resins and fatty acid soaps.
 20. The safety cushion system ofclaim 6, wherein said mixture of said Indonesian rubber and processedbulk of natural rubber lattice of said anchoring bolt composition isfurther of a ratio of 0.8-1.2:1.
 21. The safety cushion system of claim20, wherein said processing aid agent of said anchoring bolt compositionis further applied in a total amount of 8-12 parts by weight.
 22. Thesafety cushion system of claim 21, wherein said mixture ofstyrene-butadiene resin, penachlorothiophenol and alkylphenolformaldehyde resin of said anchoring bolt composition is further of aratio of about 10-20:1:5-10.
 23. The safety cushion system of claim 22,wherein further said pine tar medium of said anchoring bolt compositionis applied in an amount of 1-3 parts by weight.
 24. The safety cushionsystem of claim 23, wherein said filler of said anchoring boltcomposition is further applied in a total amount of 60-80 parts byweight.
 25. The safety cushion system of claim 24, wherein said colorantof said anchoring bolt composition is selected from the group consistingof red iron oxide, yellow iron oxide, titanium dioxide and carbon black.26. The safety cushion system of claim 25, wherein said mixture ofcolorant and amorphous silica of said anchoring bolt composition is of aratio of 4-8:1.
 27. The safety cushion system of claim 24, wherein saidantioxidant of said anchoring bolt composition is further applied in atotal amount of 1-5 parts by weight.
 28. The safety cushion system ofclaim 27, wherein said mixture of polymerized1,2-dihydro-2,2,4-trimethylquinoline and N-phenyl-N(1,3-dimethylbutyl)p-phenylene diamine of said anchoring bolt composition is of a ratio of0.5-2:1.
 29. The safety cushion system of claim 28, wherein saidantiozonant of said anchoring bolt composition is further applied in anamount of 1-5 parts by weight.
 30. The safety cushion system of claim29, wherein said activator of said anchoring bolt composition is furtherapplied in a total amount of 6-8 parts by weight.
 31. The safety cushionsystem of claim 30, wherein said mixture of zinc oxide and stearic acidof said anchoring bolt composition is of a ratio of 1-5:1.
 32. Thesafety cushion system of claim 31, wherein said accelerator of saidanchoring bolt composition is further applied in a total amount of 2-4parts by weight.
 33. The safety cushion system of claim 32, wherein saidmixture of 4-morpholinyl-2-benzothiazole disulfide,4',4'-dithiodimorpholine and tetramethylthiuram disulfide of saidanchoring bolt composition is of a ratio of 1-3:1:0.2-1.
 34. The safetycushion system of claim 33, wherein said vulcanizer of said anchoringbolt composition is further applied in an amount of 0.4-0.8 parts byweight.
 35. The safety cushion system of claim 34, wherein saidpre-vulcanizer inhibitor of said anchoring bolt composition is furtherapplied in an amount of 0.05-0.15 parts by weight.